Java does not execute all commands in shellscript with Apache commons exec

Question

I'm getting such an strange behavior here.

I have the following method:

public static void loadMonitorsFromCron(){  
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    File ism_dir = new File("/var/app/ism/");
    String line = "/usr/bin/ksh /var/app/ism/ism_check_cron.ksh";
    CommandLine commandLine = CommandLine.parse(line);          
    try {
        DefaultExecutor exec = new DefaultExecutor();           
        PumpStreamHandler streamHandler = new PumpStreamHandler(outputStream);          
        exec.setWorkingDirectory(ism_dir);          
        exec.setStreamHandler(streamHandler);           
        exec.execute(commandLine);          
    } catch (ExecuteException e1) {
        System.out.println("ERROR: "+e1.getMessage());
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (IOException e1) {
        System.out.println("ERROR: "+e1.getMessage());
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }       
    String[] paths = outputStream.toString().split("\n");

    System.out.println("Paths: ");
    for(int i=0;i<paths.length;i++)
        System.out.println(paths[i]);

    loadErrorCodeFromPath(paths);       
}

And this is the script: ism_check_cron.ksh I am trying to execute:

#!/usr/bin/ksh

echo "inbound_monitor.ksh"
echo "$(crontab -l | grep ism | grep -v '#' | cut -d ' ' -f 6 | cut -d '/' -f 5)"
echo "ism_heapdump.ksh"

When I look the output from systemOut, I just see this:

SystemOut     O Paths:
SystemOut     O inbound_monitor.ksh
SystemOut     O
SystemOut     O ism_heapdump.ksh

The crontab -l were supossed to list many other strings like the above ones, but as you can see, I got nothing through Java.

If I execute the script in the Linux terminal it works fine. As the Java can execute 'some part' of the script I also assume that the method is also fine. So I am completely lost. Any hint?

======== UPDATE =========

Problem solved, future readers can refer to the comments below.

do you execute it from the same user (java program & direct ksh script)? If no -u option provided crontab operates on current user entries — Piotr Reszke
– Piotr Reszke, Commented Sep 27, 2016 at 20:32
It could be a good hint. Regarding the -u, I cannot use it, because: "must be privileged to use -u". I can't execute it as superuser. But there should be a way to force java to execute with a certain user, shouldn't it? — vinicius.olifer
– vinicius.olifer, Commented Sep 27, 2016 at 20:39
add the whoami > /tmp/java_whoami.txt to your ksh and check the file /tmp/java_whoami.txt if the user is the one that you expect — Piotr Reszke
– Piotr Reszke, Commented Sep 27, 2016 at 20:50
Perfect Piotr R. I did this and realize that my application was in fact running as root, so I just added the -u parameter. So simple, but I couldn't think on this. Thanks a lot. — vinicius.olifer
– vinicius.olifer, Commented Sep 27, 2016 at 21:26

Piotr Reszke · Accepted Answer · 2016-09-28 04:37:47Z

2

Executing crontab -l without the -u option will list only the current user crontab entries.

The solution is to point the actual user with the -u parameter:

echo "$(crontab -u myuser -l | grep ism | grep -v '#' | cut -d ' ' -f 6 | cut -d '/' -f 5)"

Second solution is to add all crantab entries for user that is running your java program and remove entries from the user that doesn't need them.

answered Sep 28, 2016 at 4:37

Piotr Reszke

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vinicius.olifer · Accepted Answer · 2016-09-27 21:40:22Z

0

Java was running with a user I was not expecting. Following @Piotr R advice, I solved this by adding the -u parameter in the crontab -l command:

echo "$(crontab -u myuser -l | grep ism | grep -v '#' | cut -d ' ' -f 6 | cut -d '/' -f 5)"

edited Sep 27, 2016 at 21:40

answered Sep 27, 2016 at 21:31

vinicius.olifer

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